1. Field of the Invention
This invention generally relates to apparatus for collecting spilled oil floating on the water surface, for example, in a bay, harbor or lake, and particularly to a spilled oil processing apparatus preferably in the form of a catamaran for collecting spilled oil floating on the water surface by having it once gelled.
2. Description of the Prior Art
The present inventor previously invented a work ship in the form of a catamaran having a rotating impeller for collecting solid objects drifting on the water surface and it has since then been used in various fields thereby verifying its effectivity. This work ship is disclosed in Japanese Utility Model Publication No. 57-18238. Since the above-described work ship was developed exclusively for collecting solid drifting objects, it cannot be used for collection of particular liquid such as spilled oil drifting on the water surface. However, since oil may be produced only at selected places on the earth and it is necessary for daily life all over the globe, it must be transported to various other places. For this purpose, marine transportation has been increasingly used, and, thus, the occurrence of oil spillage has also increased thereby bringing about various problems such as killing of fish and dirtying of coast lines. Even in bays and harbors, small spills of oil from boats and ships may accumulate and the oil spill thus accumulated can become a nuisance to users of bays and harbors such as sailors and fishermen. There is thus an increasing concern for cleaning the water surface by collecting not only solid drifts but also particular liquid, in particular spilled oil, drifting in the water surface effectively.
Various approaches have been proposed to collect spilled oil drifting in the water surface, but they are mostly too difficult and/or expensive and lack versatility in usage. For example, in the prior art, those which are suited for a large-scale operation are usually not suited for a small-scale operation, thereby necessitating the adoption of different approaches depending upon the scale of a spilled oil clean-up operation. A main technological difficulty in collecting spilled oil from the water surface resides in preferential collection of oil. That is, if water is collected together with oil, the water must be separated and returned, which would lower the operational efficiency in collection of spilled oil.
According to recent studies, there has been developed a gelling agent which causes oil to be quickly gelled when mixed at an appropriate amount (approximately 30%) thereby converting the oil into hydrophobic solids. Then, the thus gelled oil may be easily retransformed into liquid when heated to an appropriate temperature (approximately 80.degree. C.). On the other hand, if the thus gelled oil is first mixed with oil of the same quality and of the amount which is approximately ten times of the gelled oil and then heated to an appropriate temperature (approximately 80.degree. C.), then the gelling agent may be separated out thereby producing reusable oil.